Internal combustion engine



Oct. 6, 1931. E. P. DUMANOIS INTERNAL COMBUSTION ENGII IE Filed March 3, 1928 P,atented Oct. 6, 1931 EMILE PAUL DUMANOIS, OI BOULOGNE-SUR-SEINE, FRANCE INTERNAL comaus'rron ENGINE Application filed March 3, 1928, Serial No. 258,799, and in France March 15, 1927.

In the French atent in my name No. 630.216, dated the 12th of May 1926, entitled Improvements in internal combustion engines, I specified a form of combustion cham- 7 her for such engines by whose use I am enabled to extend the compression limit at which the detonation is produced and also the limit at which the self-ignition by compression or by a hot point is produced.

I obtain this result by the use of a chamber comprising discontinuous parts or by a local increase of the cross-section by means of steps or oflsets, which are adapted to extinguish the explosive wave. Due to the resulting increase in the surface of the chamber, a more approved cooling effect will be obtained.

The present invention relates to various improvements in the apparatus specified in the aforesaid patent. These improvements serve the same purpose, and they relate to devices whereby the steps will be better cooled, or to a local increase in the cross section, which has in itself a large cooling surface, and also to arrangements acting upon the temperature of the gas contained in the cylinders.

The appended drawings show by way of example various embodiments of the present invention. n

Fig. 1 is an axial section of a cylinder with lateral valves, provided with water circulation and with flanges for cooling the said steps.

Fig. 2 is a like yiew showing another appar'atus in which the flanged steps are replaced by cooled recesses in the combustion chamber. I

Fig. 3 is a diagrammatic section on the axis of a cylinder provided with lateral valves, and

Fig. 4 is a like View of a valveless clyinder provided with central ignition.

Fig. 5 is a plane View of the inner side of a cylinder head.

In the form of construction shown in Fig. 1, the combustion chamber comprises portions having a discontinuous surface such as 2, 3, 4 which form steps of a cylindrical shape. To increase the cooling, which will further the extinguishing of the explosive wave and also the limitation of the self ignition, the wlngs or flanges 5, 6, 7 are spaced upon the walls of the chamber in such manner as to be cooled by the circulation water. If the explosive wave is produced at a given time, the expansion due to the stepped disposition of the parts 2, 3, 4 when the wave attains these parts, will act to extinguish the said wave. to

Fig. 2 shows a construction in which the discontinuous surface comprises the recesses 8 and 9 which are open upon the wall of the combustion chamber and communicate with the latter by a cross section which is practically concentric with the axis of the spark mg plug.

The operation is as follows;

When the flame comes-adjacent one of the recesses 8 or 9, the increase of section due to the recess will cause a local expansion analogous to what is obtained by the increase in the section caused by a step, and the explosive wave will thus be extinguished. A like action will be produced when the flame coincides with the other recesses. 7

It should be noted that the walls of the said recesses will also considerably increase the cooling surface of the chamber, whereby a most favourable effect is obtained.

For the purpose of avoiding as much as possible the self-ignition through a hot point, it may be acted on the temperature of the fuel mixture. It is well known indeed that the burnt gases remaining. in the cylinder will be diflused in the fuel mixture, thus producing an increased temperature and a decreased quality of the same. This purpose may be met by modifying the shape of the recesses above described. 90

In order to reduce the temperature of the fuel mixture (Figs. 3 and 4), I have given to the combustion chamber a cross section which comprises one or more local increases of sec- 0 tion in the direction in which the flame is propagated, in order to extinguish the explosive wave, each local increase of section be ing due to the communication between one part f the combustion chamber with another 0 part which is sufficiently cooled, the communication being made through an aperture which is substantially perpendicular to the direction of travel of the flame.

In the construction shown in Fig. 3, the recesses or chambers 10 and 11 communicate with the combustion chamber through the respective apertures 19.-13 of relatively small section and of great length, which are prac tically normal to that direction of travel of the flame, starting from the sparking plu 14. The said recesses 10 and 11 will thus orm part of the waste space, and they will be cooled by the cooling fluid which circulates in the interior of the cylinder head 15 which is mounted on the cylinder 16.

The operation is as follows:

At the end of the discharge stroke, therecesses or chambers 10 and 11 remain filled with the highly heated burnt gas, and this is cooled by reason of the large surface of the recesses. During the suction period, due to the small section of the apertures 12 and 13, said gas remains in the chambers 10 and 11, so that only the burnt gas situated outside the said chambers will be diffused in the carburetted mixture. In this manner the gas mixture will be purer, and its temperature will rise to a smaller degree,'according as the rela tive values of said chambers are greater with reference to the total volume of the waste space. During the compression period, a certain part of the carburetted mixture will enter the said recesses and will form a diluted mixture with the burnt gas therein contained.

Then the sparking plug 14; ignites the gas, the flame proceeds into the part of the waste space outside the recesses, in a gas which is much purer than in an ordinary engine. If the volumetric compression is suflicient, the explosive wave is indeed formed, but when it comes adjacent the aperture 12, the sudden increase of the section offered to the flame by the recess 10 through the orifice 12 whose length is relatively great and may extend upon the whole surface of the cylinder head will extinguish the explosive wave, while at the same time the carburetted mixture is ignited. The said mixture will burn at a relatively slow rate due to the great amount of burnt gas therein, and it will not form an explosive wave in the recess 10, by reason of the small linear dimensions of the said recess and of the large cooling surface.

A like action takes place when the flame comes adjacent the aperture 13.

Due to the said construction, the amount of burnt gas which escapes from the recesses during the suction stroke and enters the combustion chamber is greater when the engine operates at a slower rate, so that a greater amount of fuel mixture will take the place of said escaped gas within the recesses during the compression stroke. Consequently at slower speeds and at full torque, a less pure mixture involving a smaller amount of heat is contained in the combustion chamber outside the said recesses. Since the cooling surface of the combustion chamber is always the same, the temperature of the combustlon is less, whereby all risk of detonation and of ignition by a hot oint will be obviated. Inasmuch as the sai recesses or chambers have a relatively large surface and, a relatively small volume, they will not be the seat of self-ignition by a hot point, or of detonation, in spite of the increased amount of fuel mixture they contain at slow speeds and at the full torque.

The number of recesses 10 or 11 in use will obviously vary according to the bore of the cylinders, and one or more such recesses may be employed. The relation between the volume of the total space affordedby said recesses and the total volume of the waste space may vary to a great degree according to the size of the bore, to the shape of the chamber and to the compression. The variation may be from 5 to 85 per cent. One or more such recesses may be combined with the stepped arrangement specified in the aforesaid patent.

The apparatus shown in Fig. 4 relates to a valveless cylinder with central ignition; herein the recess 17 has a torus-shaped surface, and it is connected with the combustion chamber by a narrow orifice 18. The sparking plug is situated at 19. The annular steps 2021 are formed in the cylinder head.

The operation is the same as in the preceding case. The gas is ignited at 19, and when the flame attains the orifice 18, the cross section is suddenly increased, and the explosive wave-if produced-will thus be extinguished. The steps 20 and 21 serve for a like purpose.

Obviously, the said invention is not limited to the apparatus herein described which are given merely by way of example. It is obvious that chambers or recesses such as 1011-17, instead of being disposed upon the cylinder head, may be disposed upon the end of the piston or on the upper wall of the cylinder, or upon both of these surface por' tions, and said parts may be combined with suitable steps.

Having now described my invention, what I claim as new and desire to secure by Letters Patent is:

1. In a cylinder of internal combustion engine the rovision of means whereby the dead space 1s divided in a plurality of separate spaces, each of which is in permanent communication through a small passage with a common space, the outline of said passage is drawn so as to be substantially erpendicular in each of its oints to the direction of travel of the explosive wave at the same point.

- 2. In a cylinder of internal combustion engine, a hollow closin end for said cylinder adapted to receive a re igerating fluid, ignition means communicating with the combustion chamber, and hollow members rovided on an integral with the inner wa of $8.1 closing en and projectin into the refrig- 5 crating fluid, each of sad hollow members being 1n permanent communication only with the combustion chamber through a continuous slot in said wall, the section oi passage of said slot is small with relation to the capacity of said hollow member, said members and slots being disposed about the ignition means in arc concentric therewith.

3. In a cylinder of internal combustion engine, a combustion chamber wherein the dead space includes at least two separate chambers in communication with each other threugh a small passage extending in such a directlon that it will be at each point substantially perpendicular to the direction of go travel of the explosive wave at the same point.

4. In a cylinder of internal combustion engine, a closing end for said cylinder, ignition means in communication with the comas bustion chamber, at least one hollow projecting part provided on the bottom of said closing end and in permanent communication with said combustion chamber through an uninterrupted slot cut in and extending throughout said bottom around the ignition means in arc concentric therewit 5. In a cylinder of internal combustion engine, a closing end for said cylinder, ignition means in communication with the combustion chamber, a plurality of hollow projecting parts provided on the bottom of said closing end, each of which is in permanent communication with said combustion chamber through a correspondin uninterrupted slot cut in and extending t roughout said bottom around the ignition means in arc concentric therewith, said chambers andslots being radiall spaced so as to be successively attained as t e explosive wave travels.

6. In a c linder of internal combustion engine as c aimed in claim 4, the further feature residing in that said projecting part has an annular cross-section.

In testimony whereof I have signed my name to this specification.

EMILE PAUL DUMANOIS. 

